Field of the Invention
The present invention relates to the wireless charging technology, and more particularly to a circuit with both functions of wireless power transmitter and wireless power receiver and a device thereof.
Related Art
Wireless charging technology is a technology for charging device by electromagnetic field without any wire. Wireless charging technology is evolved from the wireless power transmission technology to use the magnetic resonant to transmit the electrical charge from charger to device to resonate coil and capacitor between the charge and device to achieve a high efficient power transmission. The wireless charger is safer, no exposed connections, no leakage current. Thus, many problems in wired charger are prevented. Due to the development of the wireless charging technology, Wireless Power Consortium is established because of the situation. One of accomplishments of Wireless Power Consortium is to promote Qi standard. With the standardization, wireless charging technology is more widely adopted.
FIG. 1 shows a circuit diagram of a wireless power transmitter disclosed by the Wireless Power Consortium. Referring to FIG. 1, the label L1 represents the primary winding. The switches 101, 102, 103 and 104 form a power conversion unit to control the LC resonant circuit 105 and its output power. FIG. 2 illustrates a circuit diagram of a wireless power receiver disclosed by the Wireless Power Consortium. Referring to FIG. 2, the label L2 represents the secondary winding. The switches 201 and 202 and the capacitors C201 and C202 forms a communication module. The switches 203 and 204 and the diodes D201 and D202 forms the rectifier circuit. Since the operation of the circuit is described by Qi of Wireless Power Consortium, the detail description is omitted.
Because of rapid development of wireless charging technology, some people try to put the wireless power transmitter and the wireless power receiver into the same device, such as a mobile power bank with both functions of wireless power transmitter and wireless power receiver. In other words, the mobile power bank must have the wireless power transmitter circuit and the wireless power receiver circuit. However, in Qi, the wireless power transmitter needs one coil, and the wireless power receiver needs another coil. If one device is designed to serve as the wireless power transmitter and the wireless power receiver, it requires two coils.